The packaging of candy, lettuce and other food products in bags presents some problems. First among these is that the equipment for doing so must be constructed in such a way that it is readily sanitizable and otherwise meets standards of cleanliness such as, in the United States, regulations of the Federal Government.
Bulky food products such as leaf lettuce present special problems. One of the problems is substantial quantities of air are in a lettuce-filled bag. Further, if the lettuce is wet, surfaces to be sealed become wetted, inhibiting proper sealing.
The use of chains of pre-opened bags to form packages is now well known. Such chains of bags are disclosed and claimed in U.S. Pat. No. 3,254,828 entitled FLEXIBLE CONTAINER STRIPS (The Autobag Patent). A commercial version of a machine described and claimed in U.S. Pat. No. 3,965,653 entitled PACKAGING APPARATUS, and in other patents deriving from the applications that resulted in this patent, (the H-100 Patents) has been sold commercially by Automated Packaging Systems, Inc. under the designation H-100. While the H-100 machine has been very successful it is a machine in which bag separation and sealing of a loaded bag are completed before a succeeding bag is positioned in an opened condition at a load station and loaded. This sequential operation is a limiting factor on the speed at which packaging operations are performed.
Another machine which has been successfully used commercially, for bagging chickens in operations where the bags are not sealed is sold by Automated Packaging as a part of its PHS-2000 system and is the commercial version of the machine described and claimed in U.S. Pat. No. Re. 32,963 entitled PACKAGING APPARATUS AND METHOD (The Chicken Bagger Patent).
A limitation on the use of chains of interconnected pre-opened bags has been when heavy or bulky products are packaged it becomes difficult to properly register the face of the bag with the back of the bag to effect a high quality, neat appearing seal. While special techniques and equipment such as that described in U.S. Pat. No. 3,956,866 entitled PACKAGING METHOD AND APPARATUS have been developed to assist in the proper packaging of relatively bulky and/or heavy materials, the use of pre-opened bags on a roll has none the less been limited to moderate size bags. The essentially bulk packaging of such products as lettuce have at most been packaged with chains of pre-opened bags in very limited quantities if at all.
A number of proposals have been made for expelling air from loaded bags. U.S. Pat. No. 3,861,113 entitled PACKAGING APPARATUS AND METHOD (the Deflator Patent) and U.S. Pat. No. 3,477,196 entitled MECHANISM FOR AUTOMATICALLY FEEDING, LOADING AND SEALING BAGS (the Automatic Machine Patent) are examples. None have been fully satisfactory for compacting bags of leafy vegetables.
In the packaging of some materials it has been considered desirable to charge gas into the package or to evacuate the package or both. Currently, at least one state has regulations limiting the use of bag evacuators and there are those who are concerned with charging gases into gas of food products.